Tool for removing knockouts from panelboards



Dec. 3, 1963 A. R. NORDEN ETAL 3,112,352

TOOL FOR REMOVING KNOCKOUTS FROM PANELBOARDS Filed March 18, 1959 FIG FIG.4

FIG. 3

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3,112,852 TOOL FGR REMOVING KNOCKOUTS FROM PANELBUARDS Alexander R. Norden, New York, N.Y., and Fellks Tomczair, Newark, Nl, assignors to Federal Pacific Electric Company, a corporation of Delaware Filed Mar. 18, 1959, Ser. No. 800,238 2 Claims. ((11. 225-104 pressure from the lower and normally concealed surface of the panelboard.

In concept such knock-outs cannot be removed except when the panelboard is originally being installed at which time the panel is free of wiring and is readily removable so that access to the rear of the panel for knock-out removal is a simple matter. However, it develops that such panelboards after installation are legitimately required to be changed to reclassify one or more of the circuit breaker mounting regions, so that a circuit breaker of higher current rating-classification may be substituted for a previous one of lower rating, this substitution requiring removal of one or more knock-outs. In accordance with the present invention, a specialized tool which is to be available only to authorized personnel can be used to simply and conveniently remove knockouts, access to the rear surface of the knock-outs being gained through a hole through the panelboard adjacent the knock-outs.

A feature of the invention resides in a provision of a J-shaped tool having shoulders adjacent fhe curved portion of the J-shaped formation, this formation being insertable through the hole to engage the rear surface of the knock-out while the shoulder forms a fulcrum against a panelboard portion adjacent the hole about which lifting leverage can be developed for knock-out removal. The term knock-out removal is used in a general sense, inasmuch as it is not necessary for the knock-out to be completely separated from the panelboard, but only for the knock-out to be lifted away from the panel by a sufficient distance so that complete removal can be effected by prying or gripping the thus lifted knock-out made accessible for removal from the front of the panelboard.

A related object is the provision of a novel tool for modifying the rating-classification of panelboard areas raving knockouts to reclassify such areas. This aspect of the invention involves the provision of a hole through the panelboard adjacent to such knock-outs, the insertion of a hook-shaped tool therein from the front of the panelboard, and the prying operation of the tool at the front of the panelboard with the rear of the knock-out being subjected to pressure of the thus inserted hooked-shaped formation disposed to engage such knock-out.

The nature of the invention and its further objects and features of novelty will be apparent from the following detailed disclosure of the presently preferred embodiment thereof, which is shown in the accompanying drawings forming part of this disclosure. In the drawings:

FIG. 1 is a plan view of a fragmentary portion of the panelboard with a tool shown inserted through an opening therein preparatory to removal of a rating-classification knock-out;

FIG. 2 is the side elevation of the tool in position with respect to the panelboard for removal of a knock-out, the

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tool being shown in side elevation and the panelboard appearing in section;

FIG. 3 is a fragmentary cross-sectional view of a lower portion of a circuit breaker and a panelboard circuit breaker mounting region for which the knock-out removal method and tool is intended; and

FIG. 4 is a fragmentary side elevation of a portion of the tool on a greatly enlarged scale.

Referring initially to FIG. 3 of the drawings, a lower portion of a circuit breaker it is shown with its bottom wall slanted upward and away from a circuit breaker mounting region of a panel 12 against which the circuit breaker is to be installed. The circuit breaker has a recess 14 at one end that receives a hook 16 projecting from the panel which is to support the circuit breaker. A raised region or bulging formation 18 is provided at the circuit breaker mounting region on the panel. Formation 18 in FIG. 3 has a knock-out 2% in place and an open ing 22 from which a knock-out was removed. Such knock-outs are sheared from the rear of the sheet metal panel, incompletely severed therefrom, and pushed almost all the way back into position from which they were sheared. In that condition they can readily be removed by pressure applied at the rear of the knock-out, so that they can be lifted into an accessible position to be broken oif by engagement from the front of the panelboard.

Circuit breaker 10 at its bottom surface has a ratingclassification member 24 which has two legs 26 defining characteristic structure identified with the rating-classification of the circuit breaker. In the illustrated embodiment, member 24 is identified with a circuit breaker of heaviest rating-classification. Circuit breakers of the next lower rating-classification normally are provided with a rating-classification member having a single left-hand leg 26. The lowest current rating-classification of circuit breakers omits member 24- entirely and thus can be mounted in any paneboard circuit breaker mounting area. Thus the circuit breakers have structure characteristic of the rating thereof complementary to their companion circuit breaker receiving regions so as to be received only in said regions (or in a region of higher rating). The next higher classification having a rating-classification member with a single left-hand leg 26 requires the left-hand knockout to be removed as illustrated in FIG. 3 to receive said leg; and the highest of the three rating-classifications requires removal of both knockouts to receive member 24 having a pair of legs 26. It is apparent that circuit breaker 10, having a member 24 with two legs 26 may not be installed in the panel area shown in FIG. 3 inasmuch as the left-hand leg 26 of member 24 will be obstructed by knock-out 20.

It is the purpose of the present invention to provide a highly specialized tool and method of removal of an unwanted knock-out so that, by limiting distribution of the tool to authorized service personnel, the conversion of a panelboard area to accept a high-rated circuit breaker will be unders-taken in accordance with the code restrictions limiting circuit breakers of certain ratings to use with the gauge of wire of the branch circuit having a rating corresponding to the circuit breaker classification.

Such knock-outs as are illustrated in FIG, 3 can readily be removed by pressure as by use of a screwdriver from the rear of the panelboard. However the method of knock-out removal and the tool to be described facilitates knock-out removal during the original installation of the panelboard with its complement of circuit breakers of various ratings, in addition to its vital indispensable role in knock-out removal after installation of the panelboard in a box where the rear surface of the knock-out is inaccessible.

The tool to be described in detail can be used to lift knock-out 20 away from the panel a sufiicient distance so that complete removal can be effected and thus clear the way for the left-hand leg 26 of rating-classification member 24 of the circuit breaker 18 illustrated so that the latter may be installed in position in the now modified. mounting area. The rating-classification area 13 would then have two openings to receive companion legs 26 of' rating-classification member 24'.

In FIGS. 1 and 2, a one-piece sheet metal tool 28 is illustrated having an elongated body portion comprising a generally flat body part 30, and two integral shaped. end portions 32 and 34. It will be noted that end por tions 32 and 34 include relatively short but Wide terminal parts 35a and 35b of the elongated body portion, and depart from the plane of the generally fiat body portion 38 and form obtuse angles therewith. The obtuse anglesavoid interference between the body portion 30 and the panelboard when the tip of the tool is initially being introduced into the panel opening, shown in dotted lines 28 in FIG. 2. Portion 32 has shoulders 36 and a narrowed curled or hook formation 38 that terminates in a wedgeshaped end portion 40. In end portion 32 of the tool, there is seen to be an abrupt transition between the short and wide terminal part 35a and the narrow curled formation 38 which defines shoulders 36. The outer surface 49a of the wedge portion is curved and has a radius centered approximately at shoulder 36, so as to be approximately part of a cylinder having an axis lying generally along shoulders 36. Hook formation 38 is disposed medially of the width of tool 28 and extends from should-- ers 36 which define terminal edges of the inclined end portion part 35:: forming part of the body portion. The hooked formation 38 is of uniform width and thickness to the wedge-shaped end portion 49 which tapers slightly in thickness towards the terminal edge thereof as shown in FIGS. 2 and 4. The foregoing shape is required for maximum strength, inasmuch as there is only a restrictedsize hole through the panel for access to the underside of the knock-out. This is better illustrated at the righthand side of P168. 1 and 2, where the hook formation 42 is shown extended through a hole '44 in the panel 12 adjacent to the two rating-classification knock-outs. Hook 42 corresponds to hook 38 and has the same form of shoulders and the same wedge-shaped end as that of hook 38, except that hook 4 2 is of larger radius (approximately twice the radius of hook 38 measured from the shoulders) so as to engage the right-hand knock-out as illustrated, hook 38 being of much smaller radius so as to engage the knock-out closer to hole 44. By inserting a hook 38 or 42 in the manner illustrated, and then using downward leverage on the opposite end or handle portion 32, 34, the shoulders of the tool serving as a fulcrum against a companion panel edge at hole 44, upward pressure can be exerted against the knock-out engaged by the tool. After the knock-out has been lifted some minimum distance, it can be grasped from above the panelboard so that complete removal can be effected to leave an unobstructed hole or opening.

The panelboard illustrated has a number of elements 46 which cooperate with recesses of certain circuit breakers to locate in position such circuit breakers for which the panelboard is designed. These locating elements 46 are in the form of integral tongues struck from the panel and they leave holes 44 at formations 18 that are here utilized for access by the tool 28. The tool is formed with a hole 50 in predetermined position adjacent each end so that operation of the tool is not obstructed by locating element 46.

The cross-section of the J-shaped or curled or hooked end part of the tool which penetrates the panelboard is of limited cross-section and the body portion 30 of the tool adjacent hole 58 is also of limited cross-section, and there is the possibility of excessive strain being imposed on the tool if it is levered too far. However, in the aforedescribed panelboard installation hook 16 projects from the panel in the path of movement of the tool during knock-0ut removal so that such hook 16 serves as a stop for the tool to prevent excessive leverage from being imposed on the latter. By the time the tool engages the hook 16, the knock-out has been lifted to an accessible position for removal. An enclosing box for the panelboard is shown in phantom in the drawings.

From the above it will be apparent that by the use of the above described tool and knock-out removal technique knock-out removal is facilitated during the original installation of the paneiboard as well as assuming a virtually indispensable role in providing for knock-out removal after installation in which the rear surfaces of the knock-outs are inaccessible. Thus the tool permits anthorized personnel to conveniently legitimately reclassify the circuit breaker mounting regions of panelboard installations from the front thereof, access to the rear surface of the knock-outs being obtained through openings provided in the panelboard.

Various additional modifications of the above embodiments of the invention will readily occur to those skilled in the art, and therefore the invention should be broadly construed in accordance with its full spirit and scope.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A one piece sheet-metal tool for changing the ratingclassifications of panelboards having at least one knockout adjacent to an opening therethrough, including a body portion of relatively great width having an obtuse angled bend therein dividing the body portion into a relatively long flat part and a relatively short terminal part, and a smoothly but prominently curled end formation of substantially smaller width extending integrally from said terminal part, said bend and said curled formation facing generally oppositely and being thus sinuous, said curled formation being of substantially uniform width and thickness except for the free end portion thereof, said end portron being wedge-shaped and being remote from said relatively short terminal part, the transition in width of the tool between said short terminal part and said curled end formation being abrupt and thus defining laterally extending shoulders.

2. A one-piece sheet-metal tool in accordance with claim 1, wherein the outer surface of said wedge-shaped portion of the curled formation is disposed at least approximately in the surface of a cylinder having its axis lying generally along said shoulders.

References Cited in the file of this patent UNITED STATES PATENTS Re. 15,388 Fleming June 20, 1922 441,113 Sostmann Nov. 18, 1890 1,344,619 Colvin June 29, 1920 1,370,397 Axelton Mar. 1, 1921 1,472,833 Herold Nov. 6, 1923 1,702,149 Brown Feb. 12, 1929 2,263,875 Johnson Nov. 25, 1941 2,429,327 Morgan Oct. 21, 1947 2,429,967 Sorensen Oct. 28, 1947 2,638,025 Nelson May 12, 1953 2,718,057 Hammond Sept. 20, 1955 FOREIGN PATENTS 789,829 Great Britain J n. 29, 9 8 

1. A ONE PIECE SHEET-METAL TOOL FOR CHANGING THE RATINGCLASSIFICATIONS OF PANELBOARDS HAVING AT LEAST ONE KNOCKOUT ADJACENT TO AN OPENING THERETHROUGH, INCLUDING A BODY PORTION OF RELATIVELY GREAT WIDTH HAVING AN OBTUSE ANGLED BEND THEREIN DIVIDING THE BODY PORTION INTO A RELATIVELY LONG FLAT PART AND A RELATIVELY SHORT TERMINAL PART, AND A SMOOTHLY BUT PROMINENTLY CURLED END FORMATION OF SUBSTANTIALLY SMALLER WIDTH EXTENDING INTEGRALLY FROM SAID TERMINAL PART, SAID BEND AND SAID CURLED FORMATION FACING GENERALLY OPPOSITELY AND BEING THUS SINUOUS, SAID CURLED FORMATION BEING OF SUBSTANTIALLY UNIFORM WIDTH AND THICK- 